Following approval by the FDA and the Committee on Clinical Investigations, we have started a preliminary feasibility study of the ability of a synthetic polypeptide (Copolymer I) to significantly alter the course of the disease process in patients affected by either the exacerbating-remitting or chronic-progressive form of MS. During this period, we will note whether any undesirable or desirable changes occur during and after the course of 6 months of COP I injections. We will also attempt to establish a dosage schedule. If warranted by the present studies, a formal double-blind clinical trial will be instituted to determine whether COP I is, in fact, effective in arresting or reversing the course of the disease process. COP I in normal saline or the placebo of saline alone will be injected intramuscularly over a period of 6 months. The evaluations of the patients neurological status will be performed before institution of COP I, 3 weeks, 3 months, 6 months and 1, 2, 3 and 4 years afterward. The degree of involvement will be recorded according to the Kurtzke functional and total disability scores. Where possible, objective methods of evaluation, such as visual and sensory evoked responses, as well as the usual visual and bladder function studies will be included. Routine clinical studies - blood and urine analyses, EKG, chest x-ray - will be performed before, during and after the period of treatment. Experimental studies will include evaluations of suppressor-T cells in the peripheral blood, blast transformations of circulating lymphocytes, tissue culture determinations of demyelinating potency of serum and circulating cells and similar examinations in the rabbit eye and evaluations of CSF and serum for immunoglobulin concentrations.